Quarter-turn stairs calculator with 3 kite winder steps (90 degrees turn), L-shaped

Quarter-turn stairs calculator with 3 kite winder steps (90 degrees turn), L-shaped

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the Calculator will be available after changes in the relevant parameters.
Click "Calculate" to open the options window.
Choose Drawing:
Distance: 0
Calculation resultsStaircase dimensions
  • Pitch (Angle): 31.61 °
  • Rise: 16.67 mm
  • Tread Depth: 29.88 mm
  • Going: 27.08 mm
  • Number of Steps: 17 pcs.
  • Stairs Width: 100 mm
  • Minimum Stringer Throat depth (width): 15.81 mm
Bottom Stringers of Winder Steps Block
  • Minimum Stringer Throat depth (width): 29.33 mm
Upper Stringers of Winder Steps Block
  • Minimum Stringer Throat depth (width): 21.49 mm
Materials for constructionBottom Stringers (straight flight)
  • Maximum Width: 12.67 mm
  • Stringer Length: 27.08 mm
  • Thickness: 6 mm
  • Quantity: 2 pcs.
  • Wood Volume: 0.004 m3
Winder Stringer (lower)
  • Width: 40 mm
  • Length: 108.76 mm
  • Thickness: 6 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.026 m3
Winder Stringer (upper)
  • Width: 37.52 mm
  • Length: 110.76 mm
  • Thickness: 6 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.025 m3
Upper Stringers (straight flight)
  • Width: 30 mm
  • Length: 423.07 mm
  • Thickness: 6 mm
  • Quantity: 2 pcs.
  • Wood Volume: 0.152 m3
Bottom Winder Tread
  • Tread Depth: 61.5 mm
  • Tread Length: 100 mm
  • Tread Thickness: 4 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.006 m3
Middle Winder Tread
  • Tread Depth: 64.08 mm
  • Tread Length: 133.27 mm
  • Tread Thickness: 4 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.009 m3
Upper Winder Tread
  • Tread Depth: 51.71 mm
  • Tread Length: 114.14 mm
  • Tread Thickness: 4 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.006 m3
Steps of Straight Flight
  • Tread Depth: 29.88 mm
  • Tread Length: 100 mm
  • Tread Thickness: 4 mm
  • Quantity: 14 pcs.
  • Wood Volume: 0.167 m3
Risers of Straight Flight
  • Width: 12.67 mm
  • Length: 100 mm
  • Thickness: 1.8 mm
  • Quantity: 14 pcs.
  • Wood Volume: 0.032 m3
Riser of Bottom Winder Step
  • Width: 12.67 mm
  • Length: 100 mm
  • Thickness: 1.8 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.002 m3
Riser of Middle Winder Step
  • Width: 12.67 mm
  • Length: 105.88 mm
  • Thickness: 1.8 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.002 m3
Riser of Upper Winder Step
  • Width: 12.67 mm
  • Length: 104.17 mm
  • Thickness: 1.8 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.002 m3
Balustrade
  • Handrail Width: 8 mm
  • Handrail Thickness: 4 mm
  • Balustrade Length: 471.13 mm
  • Wood Volume: 0.015 m3
Balusters
  • Baluster Width: 5 mm
  • Length: 86.84 mm
  • Quantity: 15 pcs.
  • Wood Volume: 0.033 m3
Corner Newel Post
  • Width: 8 mm
  • Length: 106.67 mm
  • Quantity: 1 pcs.
  • Wood Volume: 0.007 m3
Supporting Posts
  • Width: 10 mm
  • Length: 200.67 mm
  • Wood Volume: 0.02 m3
Joists Supporting Stair Turn
  • Width (material): 15 mm
  • Length (material): 80 mm
  • Thickness: 5 mm
  • Quantity: 2 pcs.
  • Wood Volume: 0.012 m3
  • №1 Joist Width: 15 mm
  • №2 Joist Width: 15 mm
Initial parametersDisplay
  • Units: cm mm
  • Color drawing: paint mm
Type of Stair
  • Left Turn:  selected
Type of winder steps connection to Newel Post
  • Notched post and treads:  selected
Stairs dimensions, Stairwell
  • Total Rise (from finish floor - to finish floor): 300 mm
  • Total Run: 452 mm
  • Staircase Width: 100 mm
Calculate Total Run along:
  • Upper stair flight:  selected
Steps of Straight Flight
  • Number of steps, bottom flight: 1 pcs.
  • quantityWinder: 3 pcs.
  • Number of steps, upper flight: 13 pcs.
  • quantityTotal: 17 pcs.
Risers
  • Riser Thickness: 1.8 mm
Stringers of Straight Flight
  • Thickness: 6 mm
  • Width: 30 mm
Stringers of Winder Steps Block
  • Thickness: 6 mm
  • Width: 40 mm
Joists Supporting Stair Turn
  • Thickness: 5 mm
  • Width: 15 mm
Supporting Posts
  • Post Width: 10 mm
Upper Floor Slab
  • Slab overlap above bottom of stairs (Total Run minus Stairwell): 100 mm
  • Distance from wall to slab: 0 mm
  • Slab Thickness: 20 mm
Balustrade
  • Handrail Height: 90 mm
  • Baluster Width: 5 mm
  • Handrail Thickness: 4 mm
  • Handrail Width: 8 mm
Wall
  • Wall Thickness: 20 mm
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L-shaped winder stairs calculator with 90 degree turn KALK.PRO allows you to get a ready-made design project online without a specialized knowledge and education, based on measurements of the existing Stairwell opening.

As a result of calculations, you'll get:

  • all necessary staircase dimensions and technical drawings,
  • an optimal amount of materials required for building structure,
  • detailed drawings of the assembled structure and all elements separately,
  • an adaptive 3D model in real proportions with a separate set of functional elements,
  • and recommendations for creating the most convenient and ergonomic design.

Please make sure your stair design complies with all local building codes and regulations requirements! It is very crucial step.

Staircase with winder treads is significantly space saving construction, in comparison to a staircase with a landing. Winder treads (wider at one side, do not have parallel edges) change the direction of the staircase, turn the flight. Kite winder stairs - L-shaped sraircase design consisted of 3 winder steps in a turn of 90 degrees (middle step is a kite winder).

 

Calculation of winder staircase dimensions, step by step

  • Step 1. Select the number of winder steps - 2 pcs, 3 pcs, 4 pcs, N pcs ( 3 pcs by default).
  • Step 2. Select the appropriate units of measurement (mm, cm, m, inches, ft) and the color of drawings - b&w, color.
  • Step 3. Determine the type of staircase rotation - with a left turn (left-handed stairs), with a right turn (right-handed).
  • Step 4. Select the method of newel post / winder treads joint: notched treads are fitted into notched newel; newel installation onto the surface of treads (f.e. with fasteners).
  • Step 5. Measure and enter the dimensions of staircase and stairwell opening - the width of the stairs, the Total Run and Total Rise - FFL to FFL (if the top step is at the level of the upper floor, the height of the opening = the height of the stairs).
  • Step 6. Specify the parameters of steps, risers (you can disable risers calculation, if necessary, by clicking on the checkbox) - the number of steps, thickness, nosing overhang, top step is below the upper floor level or at the level.
  • Step 7. Enter the stair stringer parameters, posts and joists  - supporting the 90 degree turn of the stairs.
  • Step 8. Determine the dimensions of the railing system.
  • Step 9. The parameters of the upper floor slab and walls are used only for 3D-visualization and do not affect the final results.
  • Step 10. Confirm the entered values ​​and start the calculation of the winder stairs using the "Calculate" button.

Finally, you get an estimated material quantity, the dimensions of staircase elements. Click on the "View in 3D" tab to view interactive 3D model. On the tab "Download" you can choose saving method of your calculation results and drawings or 3d objects.

Design features in the drawings

Stairs layout
The drawing of the stair stringer

The direction of the fibers inside of the stringer

The direction of the fibers inside of the stringer

The direction of the fibers inside the winder treads

The direction of the fibers inside the winder treads

The direction of the fibers inside stage

The direction of the fibers inside rectangular treads

Recommendations

To create the most comfortable stair structure it is recommended to select the steps dimensions on the basis of the universal formula of a “perfect staircase” by French engineer François Blondel. If the step width decreases, it is necessary to increase its height, and vice versa - if the step width increases, its height must be reduced, while maintaining the step length in the range of 630-650 mm.

Blondel's formula: 2 × Rise + Run = 63  ÷ 65 cm

  • Rise – the height of the step;
  • Run – tread width or going;
  • 63 ÷ 65 cm average stride length of a person.  The IRC limit gives a 2r+R of 25 ½

One more rule "Rise + Run" says that rise plus run should equal 18 inches (17 -19). The IRC limit gives an r+R of 17 ¾ 

 

Building regulations

 Your staircase should be compliant with national building codes, local regulations (depending on country and city you live in): 

  • BCA (Building Code of Australia)
  • UK  Building Regulations 2010 Part K
  • IRC (International Residential Code) for residential buildings, IBC (International Building Code) — the United States of America
  • NBC (National Building Code of India).

 The International Residential Code (IRC 2018) says :

  • "R311.7.5.2.1 Winder treads.  Winder treads shall have a tread depth of not less than 10 inches (254 mm) measured between the vertical planes of the foremost projection of adjacent treads  at the intersections with the walkline . Winder treads shall have a tread depth of not less than 6 inches (152 mm) at any point within the clear width of the stair. Within any flight of stairs, the largest winder tread depth at the walkline shall not exceed the smallest winder tread by more than 3/8 inch (9.5 mm)..."
  • "R311.7.4 Walkline.  The walkline across winder treads and landings shall be concentric to the turn and parallel to the direction of travel entering and exiting the turn. The walkline shall be located 12 inches (305 mm) from the inside of the turn. The 12-inch (305 mm) dimension shall  be measured from the widest point of the clear stair width  at the walking surface..."
  • Minimum Going or Run (width of tread without nosing overhang) must be not less than 10 inches (254 mm), according to R311.7.5.2. 
  • Headroom - shall be not less than 2032 mm or 6 ft 8 inch (R311.7.2).
  • Handrail height - 864 ÷ 965 mm or 34 ÷ 38 inches (R311.7.8.1)
  • Risers or steps height - max. height 196 mm or 7 3/4 inches (R311.7.5.1)
  • Nosing projection - 19 mm ÷ 32 mm (3/4 ÷ 1 1/4 inches), according to R311.7.5.3.
  • Staircase clear width - not less than 914 mm, 36 inches (R311.7.1)
  • Vertical Rise of staircase flight - less than 3835 mm or 151 inches (R311.7.3)

Using KALK.PRO is very simple – requires no special knowledge, just enter a few values and you will be able to get a professional design of the staircase with winder steps for free (drawings - are available for premium users).

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Specify dimensions
Display
DU
CL
Type of Stair
LF
RG
Type of winder steps connection to Newel Post
LOC
INT
Stairs dimensions, Stairwell
Y
X
Z
Calculate Total Run along:
FTP
FBT
Steps of Straight Flight
QB
1
QT
13
SW
SF
SP
Risers
H
HT
Stringers of Straight Flight
T
WI
Stringers of Winder Steps Block
IT
IW
Joists Supporting Stair Turn
JT
JW
Supporting Posts
SB
Upper Floor Slab
SX
WX
ST
Balustrade
RH
BA
RT
RW
Wall
WT